Rabies virus infections pose a continuing threat to man and his domestic animals. Wildlife epizootics continue spreading, resulting in increasing numbers of post-exposure human immunizations. Pre-and post-exposure vaccine failures occur both in humans and in laboratory animals sometimes even in the presence of viral neutralizing antibody. The long-term goal of research in this laboratory is to uncover the reason(s) for these vaccine failures. The purpose of our current research is to determine, first, whether or not one high affinity receptor for rabies virus is the acetylcholine receptor (AChR) or a closely-related molecule. Secondly, experiments will be undertaken to relate vaccine failure to development of anti-idiotypic (possiblely anti-receptor) antibody. Host-cell receptor identity on muscle cells at neuromuscular junctions will be identified by use of the anti-idiotypic network. Monoclonal antibodies to neutralizing/attachment epitopes of the viral glycoprotein will be used as immunogens to produce anti- idiotypic antibody (anti-receptor) antibody. Binding of anti- idiotypic antibody to subunits of the AChR (or associated molecules) will be determined by immunoblotting. To confirm rabies virus binds to the AChR, monoclonal antibodies to relevant subunits of the AChR will be used as immunogens to produce anti- rabies virus neutralizing antibody. Anti-idiotypic antibodies will be used to map virus-specific receptors in both the peripheral and central nervous system. Virus antigen and host cell receptors will be co-localized at synaptic junctions by immunoelectron microscopy. Receptor identity will be confirmed by immunochemistry. To correlate vaccine-failure with development of anti-idiotypic antibody, vaccinated mice will be monitored by ELISA for development of anti-idiotypic antibody which either mimics the immunizing antigen or is anti-receptor antibody.